Gelatin or collagen hydrolysate containing drug formulation that provides for immediate release of nanoparticle drug compounds

ABSTRACT

Nanosols and process for preparing the same allow colloidally dispersed solutions of scarcely water-soluble active substances to be stabilized with gelatin or its derivatives, by partly or fully setting the iso-ionic point (IIP, equivalent to a neutral charge) between the gelatin and the surface charged active substance particles. In order to neutralize the charge of the system composed of active substance particles and gelatin, the surface charge of the particles is compensated by a corresponding opposite charge of the gelatin molecules. For that purpose, a determined charge in relation to the isoelectric point (IEP) and the pH value of the solution is set on the gelatin molecules. By stabilizing in this way the practically monodispersed state thus generated, the Ostwald maturation of the colloidal particles of scarcely soluble active substance is strongly reduced. A new form of pharmaceutical administration having new properties can thus be obtained with generally scarcely water-soluble inorganic and organic compounds, in particular medicaments with a problematic bioavailablity. Preferred medicaments are glibenclamide and 3-indolylacetic acid derivatives, such as indomethacin or acemetacin.

The present invention relates to a process for the preparation of acolloidally disperse system of poorly water-soluble pharmaceuticalsubstances or of poorly water-soluble inorganic and/or organiccompounds. It furthermore relates to a pharmaceutically administrablenanosol, i.e. a stable colloidally disperse system of poorlywater-soluble pharmaceutical substances with gelatin. It furthermorerelates to an immediate-effect medicament for the treatment of rheumaticand/or inflammatory diseases, which contains a 3-indolylacetic acidderivative. It finally relates to an immediate-effect medicament for thetreatment of diabetes, which contains glibenclamide.

The difficulty of bringing pharmaceutical substances with problematicbioavailability into a satisfactory pharmaceutically administrable formis generally known. About 30% of all active compounds in medicaments areincluded under this group. A rapid release of the active compound fromits preparation after administration, i.e. in general a rapid conversioninto the dissolved, absorbable form must be demanded of them in order toachieve an acceptable therapeutic result. If it is assumed that theabsorption process in vivo is not the rate-determining step, alltechnological processes for improving pharmaceutical substance releasecan be attributed to the influencing of two parameters in the so-calledNoyes-Whitney equation: ##EQU1## where dc/dt: amount of solid going intosolution per time=rate of solution,

D: diffusion coefficient of the substance molecule concerned

A: effective solid or crystal surface which is accessible to the solvent(wettable surface area),

d: thickness of the diffusion layer

V: solvent volume,

c_(s) : saturation solubility of the substance concerned and

c_(t) : concentration of the substance concerned in solution at time t.

This equation gives a mathematical expression for the rate of solutionof substances generally (in this case pharmaceutical substances). Inthis equation the changeable target quantities for the pharmacist areonly the saturation concentration (saturation solubility) of thepharmaceutical substance and the substance surface area which caneffectively be attacked by the solvent. An increase in these twoparameters should also result in an increase in the rate of solution.

Classical processes for increasing the saturation solubility ofpharmaceutical substances are e.g.:

a) the addition of water-miscible organic solvents, or

b) the use of hydrotropic substances.

These measures, however, have the disadvantage that on the one hand theyburden the body with toxicologically suspect substances, on the otherhand an increased solubility in vivo can be destroyed by therecrystallization processes. Often the amount to be used is additionallyinadequate to bring the necessary dose of pharmaceutical substance intosolution.

The solubilization of pharmaceutical substances by surface-active,micelle-forming substances or the formation of cyclodextrin inclusioncompounds has therefore recently been described. Both applications,however, have the significant disadvantage that primarily dissolvedpharmaceutical substance is actually not present in the body in freeform, but must be released from its complex with the auxiliary. That isto say on the whole the release of pharmaceutical substance is worsenedrather than improved. Apart from this, side effects due tosurface-active substances are not to be excluded.

An increase in the surface area of pharmaceutical substances is possibleby means of micronization. This processing, however, is very difficultand laborious and has its limit at a particle size of ≧1 μm. The smallerthe particles of powder, however, the more strongly prone they are toaerophilicity and the degree of wetting in contact with solvents(effective surface area A) becomes low--the rate of solution is ratherreduced. The addition of hydrophilic excipients is therefore almostalways necessary.

Further known processes for the preparation of small particles are e.g.the following:

Violanto (U.S. Pat. No. A-4,826,689) describes a method for thepreparation of colloidally disperse particles of water-insoluble organiccompounds. In this method, laborious test experiments are necessary todetermine optimum values for the parameters temperature, rate ofstirring and rate of addition of the aqueous precipitation liquid to thesolution of the solid compound in the organic solvent. Only keeping tothese preconditions ensures the formation of the particles described. Asubsequent separation operation is intended to free the particles fromthe organic liquid. Stabilization measures in certain circumstancesrequire a very time-consuming and expensive zeta potential measurement,according to which an addition of viscosity-increasing substances orsurfactants to the aqueous precipitation liquid is calculated which isintended to prevent particle aggregation.

Fessi (EP-A-0 275 796) describes the preparation of a likewise finelydispersed system containing pharmaceutical substances, which, however,requires a defined polymer as the carrier substance. Polymer andpharmaceutical substance are dissolved in a solvent and precipitatedusing a non-solvent. Steps must subsequently be carried out to removethe nanoparticles, e.g. by filtration or centrifugation. An addition ofstabilizer (surfactants or similar excipients) is additionally necessaryduring preparation in order to minimize particle aggregation.

In the above process, complex additives are always necessary whose useneither can be specifically predetermined nor is desirable from thereasons mentioned at the beginning (toxicological risks). Simplepreparation of stable nanosols with as few foreign additives as possibleis therefore crucial for pharmaceutically relevant applications.

J. J. Marty et al., Pharm. Acta Helv. 53, 1 (1978) pp. 17-23 describesthe preparation of gelatin nanoparticles in which active compounds canalso be included. A pH adjustment during the preparation of thesegelatin nanoparticles is proposed for desolvation and resolvation.Conversion of the medicament to nanoparticles is not disclosed.

The present invention is therefore based on the object of improving thebioavailability of poorly watersoluble pharmaceutical substances byincreasing their rate of solution without addition of harmfulauxiliaries.

The invention thus also relates to a nanosol for use in the preparationof a pharmaceutical preparation having improved bioavailability, whichcontains this nanosol as active component, and the immediate-effectmedicament concerned.

The invention furthermore relates to pharmaceutical preparations for usein the treatment of diseases e.g. cardiovascular disorders, rheumatismor gout, diabetes, etc. if they contain a pharmaceutical substance, e.g.nifedipine, indometacin, glibenclamide etc. in the form of nanoparticlesin a stable colloidally disperse system with gelatin.

80% of all diabetics suffer from type II diabetes, caused by decreasedpreparation of insulin. Sulfonylureas, such as e.g. tolbutamide, haveproven particularly effective for the treatment of this type. Continuingresearch activity led to the so-called oral antidiabetics of the 2ndgeneration, such as e.g. glibenclamide, which excels tolbutamide 300times in its hypoglycemic action in humans.

Glibenclamide, 1-{4-2-(5-chloro-2-methoxybenzamido)ethyl!phenylsulfonyl}-3-cyclohexylurea,C₂₃ H₂₈ ClN₃ O₅ S, of the formula: ##STR1## has been largely successfulin the market. As comparative in vivo studies verify, no significantdifferences can be found with respect to the bioavailability quantityserum level surface area (AUC=area under curve). Serious differencesexist, however, in the pharmacokinetic parameters c_(max) (maximum bloodlevel value) and t_(max) (the time at which the maximum blood levelvalue is achieved). With many preparations, a delayed onset of actionand a lower maximum blood level concentration can be found in comparisonto a reference preparation. In particular, however, rapid influx of theglibenclamide is desired. The immediate hypoglycemic effect ofglibenclamide is more effective, the more rapidly the active compound issystemically available compared with the carbohydrates. This results inan effective reduction and shortening of the food-related rise in theblood glucose values.

A delayed action with an immediate-effect formulation for glibenclamidecan have two causes:

(1) The preparation does not disintegrate rapidly enough, so the releaseof the active compound is delayed.

(2) The absorption of the active compound is delayed following release.

Comparative in vitro release tests show distinct differences withrespect to the tablet disintegration times. The release of some tabletsfrom various manufacturers is delayed, for example only between 50% and75% of the active compound is released after 30 minutes at pH 7.4. Sucha slow release involves various dangers, because this can lead tometabolic derangements in patients, particularly as, especially in theearly morning, the blood glucose value, as is known, is at its highest.

The second reason for the deficient biopharmaceutical quality of aglibenclamide preparation has its roots in the fact that the activecompound is not absorbed or is only absorbed to a decreased extent inthe gastrointestinal tract, especially during passage through thestomach, on account of its pH-dependent poor solubility. According tothe passive transport theory, only active compound molecules can beabsorbed which are present in dissolved and undissociated form. Thesolubility of glibenclamide is thus 1 mg/l at a pH of 1.3, 3 mg/l at pH6.0 and about 30 mg/l at pH 7.8 (the data apply for room temperature inaqueous medium). As an investigation of various absorption sites in thegastrointestinal tract shows, on administration of a dissolvedglibenclamide tablet absorption takes place most rapidly in theduodenum.

According to common pharmaceutical knowledge, the solubility of activecompounds can be increased even by the use of surfactants which,however, has the crucial disadvantage that primarily dissolved activecompound is actually not present in the body in free form, but has to bereleased from its complex (micelle etc.). This in turn results in adelayed supply of the active compound. The risk of the formation ofcoarse crystalline components by recrystallization additionallyincreases. And moreover the use of surfactants is controversial onaccount of the known side effects and possible toxicity.

As already mentioned above, the water solubility of glibenclamide ispH-dependent. This means that the transition of the active compound intothe absorbable form (dissolved and undissociated) depends on thesurrounding pH medium of the gastrointestinal tract (GIT). This aspectis worthy of mention in two kinds of respects. Physiological pHs, e.g.those of the gastric fluid, can firstly differ from patient to patient.But the pH of the gastric fluid can also change from case to case, forexample due to food absorption (light breakfast, heavy dinner). Suchinter- and intraindividual pH changes lead to a differing supply ofabsorbable components and thus to different blood levels. Thus the onsetof action, characterized by release of insulin, is associated with adecrease in blood glucose, which cannot be calculated in terms of time(and according to amount), which can lead to hypo- and hyperglycemicmetabolic states. It is common to all commercially availableglibenclamide preparations that they are dependent on such individualdifferences as a result of the pH-dependent poor solubility of theactive compound.

The invention furthermore relates to one such medicament which contains3-indolylacetic acid derivatives, particularly indometacin or acemetacinas the immediate-effect form. The invention finally relates to the useof a pharmaceutically administrable nanosol of 3-indolylacetic acidderivatives, particularly indometacin or acemetacin, for the preparationof medicaments having immediate analgesic and/or antirheumatic effect.

In spite of varied pharmaceutical developments of oral immediate-effectpreparations which have a rapid influx, to this day there has still beenno success with commercially available medicaments which contain3-indolylacetic acid derivatives, particularly indometacin oracemetacin, in matching the pharmaceutical form-dependent parameters ofactive compound release with subsequent absorption of active compound sooptimally to the physiological conditions (pH ratios in thegastrointestinal tract, gastrointestinal residence time of shapedarticles, specific absorption windows for certain active substances)that the main requirement for an immediate-effect pharmaceutical form isfulfilled:

Reduced time up to the occurrence of the plasma level maximum value(t_(max)), e.g. 1 h and less

and as a prerequisite for this absorption of the active compound whichis as rapid as possible after release from the pharmaceutical form.

This requirement should bring about a high therapeutic efficiency andthus decisively increase patient compliance.

Indometacin, (1-(4-chlorobenzoyl)-5-methoxy-2-methyl-3-indolyl)aceticacid, C₁₉ H₁₆ ClNO₄, which in the meantime is almost already to bedesignated as the classical, non-steroidal anti-inflammatory, is anactive anti-inflammatory substance which plays an important part,particularly in the therapy of immediate-effect attacks of rheumatismand gout. Other syndromes in which treatment with indometacin isindicated are e.g. rheumatoid arthritis, ankylosing spondylitis orosteoarthritis. Indometacin preparations having contents of activecompound of 25 mg and 50 mg are commercially available for this purpose.

Acemetacin,carboxymethyl(1-(4-chlorobenzoyl)-5-methoxy-2-methyl-3-indolyl)acetate,C₂₁ H₁₈ ClNO₆, is an ester of indometacin which is for the most partmetabolized to indometacin in the metabolism. Its profile of actionlargely corresponds to that of indometacin. A significant differenceshould exist, however, in the better tolerability, as acemetacin shouldonly have weakly pronounced ulcerogenic properties in contrast toindometacin.

The problem which has to be overcome in the development ofimmediate-effect preparations containing said active compounds and whichhave a rapid influx appears to be as follows, as is made clear by theexample of indometacin:

Indometacin is a virtually water-insoluble active compound acid having apK_(A) of 4.5. As in general only substances which are present in thebody in dissolved and undissociated form are absorbed, no significantabsorption of indometacin in the acidic stomach medium (pH 1) is to beexpected. Only in the course of further gastrointestinal passage (pHincrease in the duodenum) does adequate active compound dissolve suchthat absorption commences. Correspondingly maximum plasma levels onlyoccur with commercially available indometacin immediate-effectpharmaceutical forms after about 1-3 h (t_(max)). These values are to beconsidered with reservation, because as a result of strong inter- andintraindividual variations in the gastric residence time of oral,non-delayed preparations (e.g. because of the type and amount of foodabsorbed), a dose of indometacin active compound does not always reachthe above absorption range (so-called absorption window) at thepredeterminable time. Indometacin is thus one such active compound inwhich the absorption kinetics always have to be put in relation to thegastrointestinal residence time of the preparation.

Pellets or granules filled in hard gelatin capsules are therefore mainlyon the market as preparations, because these can still pass through thestomach relatively rapidly on account of their small diameter (ingeneral 1-1.5 mm). Depending on the type and amount of the foodabsorbed, the filling state of the stomach etc., average residence timesare about 100 min, but can also increase to e.g. up to 300 min.

Knowing these facts, it is easily understandable that a patientsuffering from pain takes a second or third dose even before the onsetof action of the first dose. The danger of an overdose of course thusincreases.

Gelatin is a scleroprotein obtained from collagen-containing material,which has different properties depending on the preparation process. Itconsists essentially of four molecular weight fractions which affect thephysicochemical properties as a function of molecular weight andpercentage weight content. The higher e.g. the content of microgel (10⁷to 10⁸ D), the higher also the viscosity of the aqueous solution.Commercially available types contain up to 15% by weight. The fractionof α-gelatin and its oligomers (9.5×10⁴ /10⁵ to 10⁶ D) is crucial forthe gel solidity and is customarily between 10 and 40 percent by weight.Molecular weights below that of α-gelatin are designated as peptides andcan amount to up to 80 percent by weight in conventional grades ofgelatin (low-bloom).

Depending on the working up of the raw material (acidic or basichydrolysis), gelatins are obtained whose isoelectric points aredifferent. For acidically hydrolyzed gelatins the IEP is between 6.3 and9.5 (gelatin Type A), for basically hydrolyzed gelatins it is between3.5 and 6.5 (gelatin Type B). Other IEPs can also be achieved by meansof the special preparation processes indicated below. Common to alltypes of gelatin, however, is their amphoteric behavior in aqueousmedium. At pHs which are not identical to the IEP the macromolecule isalways present in charged form.

Depending on the gelatin preparation procedure (extent of breakdown ofnative collagen and acidic or alkaline hydrolysis process), gelatin ofType A or Type B has a characteristic molecular weight spectrum ormolecular weight distribution. Table 1 indicates the molecular weightdistributions of various types of gelatin or of collagen hydrolyzates,and the percentage content (frequency) of individual molecular weightranges.

                                      TABLE 1    __________________________________________________________________________    Molecular weight distribution of various known    types of gelatin or of known collagen hydrolyzates    Molecular         Collagan                            Collagen                                  Collagen                                        Elastin    Mass Dis-         Native              Gelatin                  Gelatin                      hydrolyzate                            hydrolyzate                                  hydrolyzate                                        hydrolyzate    tribution         Collagen              Type B                  Type A                      Gelita ®                            Gelita ®                                  Gelita ®                                        Gelita ®    (kD) %    %   %   Collagel A                            Collagel D                                  Sol C Gelastin    __________________________________________________________________________    >360 100  18.0                  18.0                      0     0     0     0      285         0    7.0 9.0 0     0     0     0    145-237         0    20.0                  34.0                      1.0   1.5   0     0       95         0    26.0                  11.0                      0     0     0     0    95-50         0    16.3                  13.4                      2.6   4.0   1.1   0    50-20         0    7.4 9.1 18.0  14.5  0.3   0    20-10         0    3.9 3.8 43.0  31.5  3.7   0.2    10-5 0    3.0 3.0 15.4  20.0  12.2  5.2    5-2  0    0   0   6.0   14.0  26.0  93.9    2-1  0    0   0   7.0   8.0   23.0  0     <1  0    0   0   6.5   7.0   34.0  0    MW   360  165 185 12-18 12-18 3     2-3    __________________________________________________________________________

The predominance of an individual range compared with the othermolecular weight ranges of the same gelatin can be seen clearly in theindividual columns. This range is thus the maximum of the molecularweight distribution (it is 95 kD e.g. for the Type B gelatin shown inthe figure). The concept of the "maximum of the molecular weightdistribution", however, is to be separated strictly from the concept ofthe "average mean molecular weight". This mean value is 165 kD for thegelatin of the Type B mentioned.

Colloidal dispersions are in general metastable and therefore flocculateor sediment. As a result of the predominance of the destabilizingforces, caused by van der Waals attraction, the electrostatic repulsionof the uniformly surface-charged particles is too low so that largerparticles grow at the expense of the smaller ones, which is described asOstwald ripening.

Surprisingly, it is seen in the achievement of the abovementioned objectthat with gelatin the adjustment of its state of charge by protonationor deprotonation relative to the isoelectric point (IEP) is completelyadequate in order, according to the invention, to stabilize a poorlywater-soluble organic compound, in particular such a pharmaceuticalsubstance in the form of a nanosol.

In the context of the invention, it has now been shown that the charged,colloidal pharmaceutical substance particles are stabilized if a chargeequalization is achieved between these particles and anoppositely-charged gelatin, a collagen hydrolyzate or a gelatinderivative. This state is the isoionic point (IIP) . At the same time,it is surprisingly seen that the Ostwald ripening of the colloidalpharmaceutical substance particles according to the invention issuppressed. The particles are present almost in monodisperse form andare prevented from growth. The entire system is then described as ananosol according to the invention.

FIG. 1 shows a schematic representation of the adjustable states ofcharge of gelatins as a function of the pH and IEP, it being possiblefor the IEP to be between 3.5 and 9.5, depending on the manner ofpreparation. Below pH 3.5, nearly all types of gelatin are positivelycharged. In the basic range above pH 9.5, all types of gelatin arenegatively charged.

According to the invention the fact is therefore utilized that gelatins,collagen hydrolyzates or gelatin derivatives (nearly independently ofthe viscosity) lead to a stable colloidally disperse system in nanosolform when the isoionic state of charge is present between pharmaceuticalsubstance particles and gelatin, collagen hydrolyzate or gelatinderivative.

On the other hand, gelatins according to the prior art were onlyemployed for the stabilization of an inorganic, colloidally dispersesystem. Thus German Pharmacopoeia 9 describes a colloidal injectionsolution of radioactive gold which is prepared with gelatin. It wasmerely proposed here that the macromolecule be present as a "cementingsubstance" between the individual colloid particles and thus particleaggregation be prevented. However, nothing was known until now about thestabilization mechanism, e.g. for pharmaceutical substances.

Other international (PCT) patent applications of ALFATEC Pharma GmbH,where appropriate also the PAZ Arzneimittelentwicklungsgesellschaft mbH,of the same date relate to the immediate-effect form of 2-arylpropionicacid derivatives (81AL2731 corresponding to German Patent Application P41 40 185.9), the sustained-release form of dihydropyridine derivatives(81AL2732 corresponding to German Patent Application P 41 40 194.8), theimmediate-effect form of S- and R-ibuprofen (81AL2733 corresponding toGerman Patent Application P 41 40 179.4), the sustained-release form ofS- and R-ibuprofen (81AL2734 corresponding to German Patent ApplicationP 41 40 172.7), the immediate-effect form of S- and R-flurbiprofen(81AL2735 corresponding to German Patent Application P 41 40 184.0), thesustained-release form of S- and R-flurbiprofen (81AL2736 correspondingto German Patent Application P 41 40 183.2) and the sustained-releaseform of indolylacetic acid derivatives (81AL2737 corresponding to GermanPatent Application P 41 40 191.3). Their disclosure is also made thesubject of the disclosure of the present patent application.

The degree of loading of the nanosols according to the invention withpharmaceutical substance, expressed in g of pharmaceutical substance perg of gelatin, collagen hydrolyzate or gelatin derivative, in generaldepends on the dose of the pharmaceutical substance concerned. It can be1:200 to 1:0.5, and is customarily 1:50 to 1:1, in particular 1:20 to1:3. The nanosol is thus surprisingly directly very highly suitable forthose pharmaceutical substances which usually have to be given in a highdose, such as e.g. ibuprofen (individual dose for analgesic therapy=200mg, for rheumatic therapy=400 mg). An improvement in bioavailabilityaccording to the invention in this case means a dose reduction whoserange can be crucial for a therapy. Using less pharmaceutical substance,a more efficient therapy with lower toxic burden on the body is thuspossible.

The pharmaceutical substance particles in the nanosol according to theinvention preferably have an average particle size of 10 to 800 nm, inparticular below 400 nm.

The pharmaceutical substance for the nanosols according to the inventionpreferably has a solubility in water at room temperature of less than 5g/l, in particular less than 1 g/l.

If necessary, customary pharmaceutical auxiliaries and/or othermacromolecules can be added taking into consideration the stability ofthe product according to the invention in the liquid or dried state.

Addition of e.g. polyvinylpyrrolidone has proven particularly suitablein technological terms. In this case, in particular with low molecularweight PVP (e.g. PVP K 15), the stability of the nanosol is notdecreased. The quantitative ratio of gelatin to polyvinylpyrrolidone inthis case can be, for example, in the range from 5:1 to 500:1.

Nanosols may be suitable for the customary types of administration. Forexample, when using cold watersoluble/modified gelatin the nanosolsaccording to the invention are suitable for use as parenteralpreparations. Modified gelatin can be e.g. a commercially availableplasma expander. In addition, the nanosols can be used for pulmonaryadministration or for transdermal application (e.g. semi-solidpharmaceutical form). In particular, however, they are suitable forsublingual and for oral administration and for pharmaceutical formshaving bioadhesive properties.

A further advantage of the present invention results from the largewidth of variation in the types of gelatin which can be used, whichadvantageously leads to simplified technological applications. By theuse of rapidly dissolving types of gelatin, it is thus possible toachieve immediate-effect forms of the nanosol based on tablets whichconsist almost exclusively of an auxiliary (e.g. direct tableting).Moreover, a nanosol prepared according to the invention can be spray- orfreeze-dried without problems even when using high molecular weightgrades of gelatin.

Spray-dried nanosols yield an easily dosable or granulatable powderwhich can be processed to give oral pharmaceutical forms such as e.g.hard gelatin capsules, granules/pellets or tablets.

If the nanosols according to the invention (with or without customarystructuring agents) are lyophilized, particularly rapidly releasingpharmaceutical forms can be produced, gelatins having a high peptidecontent being preferred.

For the preparation of oral sustained-release pharmaceutical forms,sustained-release nanosols can be advantageously prepared, as aredescribed, for example, in the International (PCT) Patent Applicationhaving the title "Sol-gesteuerte Thermokolloidmatrix auf Gelatinebasisfur perorate Retardarzneiformen" (Sol-controlled thermocolloid matrixbased on gelatin for oral sustained-release pharmaceutical forms) fromthe same applicant on the same date, corresponding to German PatentApplication P 41 40 192.1, whose disclosure is also made a subject ofthe disclosure of the present patent application.

Details of specific pharmaceutical forms which contain poorly solubleactive compounds in immediate-effect and/or sustained-release nanosolform can be taken from the applications already mentioned.

In the formulation of immediate-effect or sustained-releasepreparations, the pharmacist makes a fundamental difference between:

1. pharmaceutical preparation, i.e. of a release of the pharmaceuticalsubstance, e.g. from a tablet in a manner which is rapid(immediate-effect form) or prolonged (sustained-release form) timewise;and

2. the pharmaceutical substance-specific absorption site, such as e.g.the stomach or specific sections of the intestine.

The nanosols according to the invention are able, independently of thepharmaceutical preparation, to be absorbed in the entiregastrointestinal region on account of their special composition. Theycan therefore be advantageously processed to give immediate-effect orsustained-release pharmaceutical forms.

FIG. 2 shows the mechanism of passive pharmaceutical substanceabsorption in the gastrointestinal tract.

Suitable pharmaceutical substances for the nanosols according to theinvention are furthermore those with problematic bioavailability, inparticular:

1. from the strong analgesics groups, e.g. morphine, dextropropoxyphen,pentazocine, pethidine, buprenorphine;

2. from the antirheumatics/anti-inflammatories (NSAR) group, e.g.indometacin, diclofenac, naproxen, ketoprofen;

3. from the β-sympatholytics group, e.g. propranolol, alprenolol,atenolol, bupranolol;

4. from the steroid hormones group, e.g. betamethasone, dexamethasone,methylprednisolone, fludrocortisone and ester, ethinylestradiol,medroxyprogesterone acetate;

5. from the tranquillizer group, e.g. oxazepam, diazepam;

6. from the α-sympatholytics group, e.g. dihydroergotamine;

7. from the hypnotics group, e.g. secbutabarbital, secobarbital,pentobarbital;

8. from the tricyclic antidepressants group, e.g. nortriptyline,clomipramine, amitryptiline;

9. from the neuroleptics group, e.g. chlorprothixen, chlorpromazine,haloperidol, trifluopromazine;

10. from the anti-gout agents group, e.g. benzbromarone, allopurinol;

11. from the antiparkinson agents group, e.g. levodopa;

12. from the coronary therapeutics or calcium antagonists group, e.g.nifedipine and other dihydropyridine derivatives, gallopamil;

13. from the antihypertensives group, e.g. clonidine, methyldopa,dihydralazine, diazoxide, renin antagonists;

14. from the diuretics group, e.g. mefruside, hydrochlorothiazide,furosemide, triamterene, spironolactone;

15. from the oral antidiabetics group, e.g. tolbutamide, glibenclamide;

16. peptide pharmaceutical substances, e.g. insulin, renin antagonists;

17. digitalis glycosides;

18. antiarrhythmics;

19. antibiotics/chemotherapeutics, e.g. nitrofurantoin;

20. antiepileptics;

21. anticoagulants;

22. spasmolytics;

23. antimycotics;

24. hormones;

25. venotherapeutics;

26. immunosuppressants, e.g. cyclosporin;

27. tuberculostatics;

28. virustatics;

29. cytostatics;

30. provitamins and vitamins;

31. phytopharmaceuticals;

32. from the group of pharmaceutical substances for the treatment ofacquired immune deficiency (AIDS).

Within the meaning of the abovementioned pharmaceutical substance list,enantiomerically pure active compounds or pseudoracemates are alsosuitable according to the invention.

Furthermore, the nanosols--according to the invention can be used foractive substances from the dietetic foodstuffs sector.

It has surprisingly been shown in the context of the present inventionthat a large number of pharmaceutical substances can be converted intonanosol form if, after selection of a suitable gelatin (Type A or B withcharacteristic isoelectric point, molecular weight, etc.) such a netcharge of the molecule is set which leads to charge neutrality (isoionicpoint=IIP) with the charged pharmaceutical substance particles and asuitable preparation according to the invention is selected for thepharmaceutical substance (acid, base or neutral substance or amphotericsubstance respectively).

Looked at pharmaceutically, the product obtained according to theinvention behaves like a true solution, but without having the problemsof the prior art; i.e. pharmacologically suspect auxiliaries can bedispensed with.

It is surprisingly seen that the presence of stable nanoparticles e.g.in the case of glibenclamide or of the poorly water-soluble3-indolylacetic acid derivatives, particularly indometacin oracemetacin, is completely adequate to achieve an absorption ofpharmaceutical substance which

a) takes place in the stomach immediately on the release of activecompound from its preparation;

b) is independent of the physiological conditions described above;

c) is independent of the physicochemical properties of the activecompound acid;

d) is nearly complete and

e) takes place without an advance active compound dissolutionequilibrium as in the conventional preparations (the active compound isavailable in absorbable form immediately at any desired site ofabsorption).

A bioavailability and influx which was previously unknown can thus beachieved with the most different types of active compound. Associatedwith this is also a reduction in the time from administration up toachievement of the plasma active compound concentration in thetherapeutic level. Additionally, the dose of active compound containedin the pharmaceutical form according to the invention is completelyutilized such that, looked at all in all, a dose reduction is achievedwith it compared with conventional preparations with comparable action.Surprisingly, it has in fact been shown that these nanoparticles in thenanosol according to the invention can pass through the gastrointestinalmembrane (be absorbed) unprevented at any desired site of absorption.They thus behave, looked at biopharmaceutically, as a true solution, butwithout being one.

It has surprisingly been shown that only nanoparticles whose size is inthe range from 10-800 nm, preferably below 400 nm, can be absorbeddirectly. These conditions are fulfilled by the glibenclamide nanosolsaccording to the invention and with 3-indolylacetic acid derivatives,particularly indometacin or acemetacin as active compound.

The advantages of this novel product are thus obvious. As a result ofcontrolled absorption of the active compounds even in the stomach, therate of influx and bioavailability of glibenclamide and 3-indolylaceticacid derivatives, particularly indometacin or acemetacin, which waspreviously to be classified as problematical on account of their poorsolubility, can surprisingly be significantly improved with asimultaneous increase in the tolerability.

The nanosols employed according to the invention are distinguished byhigh stabilities, in particular in the acidic range, withoutflocculating or crystallizing out. This means that the nanosol isavailable to the gastric mucosa for absorption for a sufficiently longperiod during the gastric residence period and independent of pHvariations which occur, e.g. due to the effect of food.

At pHs below 2, the stability of the nanosol can be further improved byselection of a type of gelatin suited to this pH range.

The particles of the nanosols, after their preparation, afterresuspension of the dried powder and after resuspension from apharmaceutical form, are present in particle sizes from 10 to 800 nm,preferably below 400 nm, and moreover in nearly monodisperse form. Inthe resuspended state, the nanosol is furthermore well dispersed in thestomach as a nanodispersion, which creates optimum conditions forabsorption. As the nano-particles are present in stabilized form, theycan be absorbed as such without them previously having to be dissolved.A solution equilibrium in advance as with micronized powders orwater-soluble salts is thus unnecessary in any case. They thereforebehave, looked at biopharmaceutically, as a true solution, but withoutbeing one of these.

For the first time, controlled absorption in the gastrointestinal tractis possible even during the gastric residence time as a result of thepresent invention. The absorption is no longer restricted to the smallintestine region; a rapid influx of glibenclamide and of 3-indolylaceticacid derivatives, particularly indometacin or acemetacin, isfacilitated.

It is thus surprisingly possible to achieve a t_(max) value of less than1 h, in particular less than 30 min, with these pharmaceuticalsubstances for the first time.

Additionally, an increase in the blood level maximum value c_(max) canalso be determined. The increase in c_(max) can therefore in certaincircumstances result in a dose reduction with the same activity.

As in vitro experiments have shown, the danger of recrystallization inthe stomach can be excluded as a result of the mentioned longstabilities of the nanosols according to the invention.

Furthermore, the immediate-effect form of glibenclamide or of3-indolylacetic acid derivatives can also be combined with asustained-release formulation of glibenclamide or 3-indolylacetic acidderivatives.

As a particular embodiment, a powdered or granulated immediate-effectnanosol can be combined with a matrix tablet, as is described in theabovementioned International (PCT) Patent Application having the title"Sol-gesteuerte Thermokolloidmatrix auf Gelatinebasis fur perorateRetardformen" (Sol-controlled thermocolloid matrix based on gelatin fororal sustained-release forms) of ALFATEC-Pharma GmbH of the same date,e.g. in a hard gelatin capsule. The contents of said application arealso made the contents of the present patent application.

Such a pharmaceutical form initially releases the active compoundrapidly and the maintenance dose (matrix tablet) constantly with highreproducibility according to a zero order rate law.

The dried nanosol can be processed to give pharmaceutical forms, forexample to give a tablet, and resuspended from this. An enteric coatingfor protection from "inactivation" of the active compounds by the acidicstomach pH is thus superfluous.

The danger of an overdose due to taking repeatedly is excluded by therapid onset of the therapeutic effect as a result of absorption in thestomach. All the disadvantages and dangers of an enteric coating areinapplicable. The present invention thus also serves to increase patientcompliance. This all constitutes a decisive contribution to themedicament safety demanded.

Fundamentally, the product according to the invention can be processedto give all pharmaceutical forms which are to be administered orally, inparticular it can be filled into hard gelatin capsules directly as apowder. It is also outstandingly suitable for direct tableting.Processing to give beverage granules, rapidly dissolving pellets orbeverage tablets is of particular interest for administration as animmediate-effect form which has a rapid influx.

In order to explain the physiological background of the absorption ofpharmaceutical substances in general and the improved absorption ratioof the nanosols according to the invention adequately, first aconsideration of the mechanism of physiological absorption ofpharmaceutical substances as is also presented in relevant publicationsis necessary. However, the present invention is neither tied to thefollowing attempt of a scientific explanation of the phenomena occurringaccording to the invention nor can it be restricted by this.

Passive pharmaceutical substance absorption takes place according to themodern state of knowledge (theory according to Brodie et al.), if thefollowing conditions exist:

a) the gastrointestinal membrane acts as a lipid barrier,

b) the pharmaceutical substance is only absorbed in dissolved anduncharged, i.e. nonionized form,

c) acidic pharmaceutical substances are preferably absorbed in thestomach and basic pharmaceutical substances preferably in the intestine.

After the oral uptake of a pharmaceutical substance into the body, itsabsorption, i.e. the crossing into the general circulation (biophase) isprevented to a great degree by physical barriers (see FIG. 2), namely

by the mucus layer and an aqueous layer adhering thereto

the cell membranes of the intestinal epithelial cells with theglycocalyx bonded thereto and

the so-called "tight junctions" which connect the epithelial cells withone another on their apical sides.

These barriers presuppose that absorption of pharmaceutical substancestakes place through the lipid double layers fundamentally independentlyof their distribution mechanism and state of charge (so-called passivediffusion).

The epithelial cells of the entire gastrointestinal tract are coveredwith a mucus layer which consists of mucins (glycoproteins),electrolytes, proteins and nucleic acids. In particular, theglycoproteins form with the main components of mucus, namely water, aviscous gel structure which primarily performs protective functions forthe underlying epithelial layer. The mucus layer is bound to the apicalsurface of the epithelial cells via the glycocalyx. The glycocalyxlikewise has a glycoprotein structure which is covalently bonded tocomponents of the membrane double layer of the epithelial cells. Thebranched polysaccharides of the glycocalyx, which are either directlycovalently bonded to amphiphilic molecules of the double membrane or toproteins incorporated in the double membrane, possess chargedN-acetylneuraminic acid and sulfate radicals and are thereforenegatively charged, which can lead to an electrostatic bond or repulsionof charged pharmaceutical substance molecules or of electrostaticallycharged particles respectively. The epithelial cell membranes consist ofphospholipid double layers in which proteins are anchored via theirhydrophobic regions. The phospholipid double layers with theirlipophilic content represent a further barrier for the transport of thepharmaceutical substances to be absorbed.

From this description, it clearly follows that charged pharmaceuticalsubstance molecules or electrostatically charged particles thereforeonly have a very low chance of being absorbed via the oraladministration route.

The nanosols according to the invention for the first time provide thetechnical teaching to form a system with which these abovementionedobstacles to absorption can be overcome. As the active compoundnanoparticles are stabilized in neutrally charged form by the gelatinaccording to the invention, they can be transported through thenegatively charged glycocalyx without relatively great obstructions, incontrast to other described nanoparticles of the prior art, which arenot or cannot be stabilized in neutrally charged form. According to theinvention, the adjustment of the isoionic state of charge canadditionally be effected in coordination with the physiologicalconditions.

As the active compound nanosols according to the invention can passthrough the glycocalyx without obstacle, without being bonded orrepelled by electrostatic effects, they thus also reach the surface ofthe epithelial cells and are available there in a high concentration.

Active, carrier-mediated transport mechanisms or phagocytosis can nowalso make a significant contribution to the absorption of the activecompound nanosols.

According to the invention, the following advantages compared with theprior art are thus especially achieved:

poorly water-soluble inorganic and organic compounds are brought into aform having novel properties;

the process is applicable to nearly all poorly soluble inorganic andorganic compounds;

it can be carried out simply and without complicated equipment andapparatuses;

pharmaceutical substances which are poorly soluble or absorbable in thebody can thus be converted into a form which behaves like a truesolution;

this takes place without chemical change, e.g. without the formation ofa derivative, or formation of a chemical complex;

this takes place without addition of surface-active or hydrotropicsubstances;

compounds which are difficult to dissolve are more rapidly andcompletely absorbable in vivo in this form;

the dose can be reduced;

the form obtained is stable on storage;

the biopolymer gelatin or its derivative is a toxicologically acceptableauxiliary;

gelatin in immediate-effect or sustained-release forms contributes togood tolerability of the pharmaceutical substance formulated accordingto the invention;

the preparation processes indicated are economical.

The system according to the invention is completely independent ofindividual differences as far as pH variations or pH effects, e.g. dueto food, are concerned. An onset of action which cannot be calculated interms of time (and according to amount), as can be the case withproducts of the prior art, is thus to be excluded and the risk of sideeffects is reduced. The present invention thus represents a decisivecontribution to the demanded pharmaceutical safety.

Fundamentally, the product according to the invention can be processedto give all pharmaceutical forms to be administered orally, inparticular it can be filled into hard gelatin capsules directly as apowder. It is also outstandingly suitable for direct tableting.Processing to give beverage granules, rapidly dissolving pellets orbeverage tablets is of particular interest for administration as animmediate-effect form having rapid influx.

In principle, all procedures and process variants and the preparation ofgelatin (Examples 1 to 3) mentioned in the present application ofALFATEC-Pharma GmbH are suitable for the preparation of the nanosolsused according to the invention. In the case of the immediate-effectform of glibenclamide, variants Nos. II and III may be mentioned aspreferably suitable processes for nanosol preparation (see below).

Gelatin is a scleroprotein obtained from collagen-containing materialwhich has differing properties according to the preparation process.Molecular weight ranges from a few thousand D up to a few million Dexist, which can be very different in their molecular weight compositionand in their physicochemical behavior. With exact knowledge of theserelationships, novel pharmaceutical applications can be found which aredistinguished by high reproducibility and simple technologicalprocessing. Details can be taken from the above-mentioned applications.With a particularly gentle preparation procedure, types of gelatin canbe obtained which only have a low content of dextrorotatory amino acidsand are thus constructed similarly to the native collagen molecule.These gelatins are distinguished, for example, by particularly goodstability properties for nanosols. Such a gelatin is advantageouslysuitable according to the invention. Depending on the working up of theraw material (acidic or basic decomposition), gelatins are obtainedwhose isoelectric points are very different. By means of specialpreparation techniques, isoelectric points can be produced specifically,it being possible to suit the molecular weight distribution to theapplication.

In the case of glibenclamide, types of gelatin are preferably suitablewhose molecular weight distribution maximum is below 10⁵ D. For tabletpreparation, as is usually predominant with oral antidiabetics, suitabletypes of gelatin are preferably those having bloom values of 0-50 and amaximum in the molecular weight distribution in the range 10⁴ -9.533 10⁴D.

With the gelatins mentioned, a weight ratio of gelatin to activecompound of 1:1 to 200:1 can be set, a higher weight ratio beingadvantageously selected during processing to give tablets etc. to avoidfurther auxiliaries (e.g. direct tableting).

Commercially available gelatins, fractionated gelatins, collagenhydrolyzates and gelatin derivatives, in particular those types whichare characterized by a low bloom number of 0 (cold water-solublegelatins or collagen hydrolyzates) up to 240 bloom, preferably 0 to 170bloom, are suitable for the nanosols used according to the inventioncontaining glibenclamide or indometacin.

In the case of glibenclamide, types of gelatin with IEPs of 3.5 to 7.5are preferably employed.

For spray- or freeze-drying of glibenclamide nanosols, addition ofpolyvinylpyrrolidone (PVP) to the aqueous gelatin solution, inparticular PVP K 15 or PVP K 25 in the weight ratio from 1:5 to 1:30 hasbeen shown to be advantageous, a readily pourable powder being obtainedwithout adverse effect on the stability of the nanosol.

In principle, commercially available gelatins, highly degraded gelatins(collagen hydrolyzates or cold water-soluble gelatin), modified gelatinsand fractionated gelatin (single fractions or mixtures thereof) are alsosuitable for the preparation of the nanosols according to the invention.

Too high a content of foreign ions (ash content >2%), however, can havean interfering effect and should be removed by deionizing using ionexchange resins (for gelatin see generally: Ullmann, Encyclopadie dertechnischen Chemie (Encyclopedia of Industrial Chemistry), 3rd Edition,1954, Vol. 10 and 4th Edition, 1976, Vol. 12, p. 211; H. E. Wunderlich:Wenn es um Gelatine geht (When to use Gelatin)--publisher: DeutscherGelatine-Verbraucherdienst, Darmstadt (1972); I. Tomka, Gelatin, in: W.Fahrig, U. Hofer, Die Kapsel (The Capsule), WissenschaftlicheVerlagsgesellschaft mbH Stuttgart, 1983, pp. 33-57.

Compared with commercially available products, the use of gelatin whichhas been prepared in a special manner leads to nanosols describedaccording to the invention having increased stability.

Examples of the preparation of grades of gelatin particularly suitableaccording to the invention are given below.

Examples of the preparation of particularly suitable types of gelatinaccording to the invention with isoelectric points of 3.5 to 9.5

EXAMPLE I Process for obtaining IEPs of 7.5 to 9.5

Collagen-containing starting material such as e.g. pig skins are treatedfor 12 to 20 hours with an aqueous solution of a 0.45N mineral acid,preferably sulfuric acid, in a liquor ratio of 1:1. The excess of acidis then removed by washing several times, it being possible to usesodium hydrogen carbonate to shorten the process. The extraction of thestock-rich material is carried out using hot water at 55-80° C. at a pHof 2.5 to 4.5. At pHs below 3.5 an IEP of 8.5 to 9.5 can be achieved, atpHs above 3.5 the IEP is 7 to 8.5. In this manner, various IEPs from 7to 9.5 can be achieved as a direct function of the pH during theextraction.

After the extraction process step, the aqueous solution is neutralizedand worked up as customary.

Depending on the temperature selected during the extraction, types ofgelatin having high to medium molecular weight distributions canfurthermore be obtained by this process.

At temperatures of 50-55° C., particularly highly viscous and high-bloomgrades are obtained. Types of gelatin having low molecular weight orcold water-soluble gelatins can be obtained by controlled degradationwith collagenases.

EXAMPLE II Process for achieving an IEP of 4 to 7.5

The collagen-containing starting material is first washed to removeforeign substances and comminuted, and then homogeneously renderedalkaline by addition of magnesite, sodium hydroxide solution or calciumhydroxide by thorough mixing in the liquor ratio 1:1.2. The materialpretreated in this way is briefly hydrolyzed by pressure hydrolysis at1.01×10⁵ to 2.02×10⁵ Pa and a pH of the aqueous solution of 8-14. Afterhydrolysis, it is immediately neutralized and the still hot aqueousgelatin solution is filtered, deionized, concentrated and dried in theusual manner.

If a weakly basic hydrolizing agent such as magnesite is taken, an IEPof 6 to 7.5 is obtained if the reaction is carried out at 1.01×10⁵ Pa.IEPs of 5 to 6 are obtained when using a dilute milk of lime suspensionand when using 0.005 to 0.1N sodium hydroxide solution IEPs of 4 to 5can be achieved.

Types of gelatin having a low degree of racemization and a low peptidecontent can be obtained with pressure ratios of 1.01×10⁵ Pa andresidence times of at most 10 min.

Medium to low molecular weight types to cold water-soluble types areproduced by correspondingly longer residence times.

EXAMPLE III Process for achieving an IEP of 3.5 to 6

Collagen-containing starting material, preferably split or ossein issubjected after the starting wash to treatment with a high-speed asher.In this case, two process variants in the liquor ratio 1:1.3 offerthemselves, which either use a saturated milk of lime suspension or a0.1 to 1N sodium hydroxide solution.

When using a milk of lime suspension, the raw material is hydrolyzed fora maximum of 3 to 4 weeks with continuous agitation. The material isthen neutralized by addition of acid and washed several times. Furtherworking up follows in the usual manner. IEPs of 4 to 6 can be obtainedin this manner.

When using sodium hydroxide solution, the asher process can be shortenedagain, the material, depending on the degree of comminution, beinghydrolyzed even after 6-12 hours at concentrations of 1N sodiumhydroxide solution. Neutralization is carried out using equimolaramounts of mineral acid and the neutral salts are removed by washingseveral times or by deionizing the aqueous gelatin solution obtained inthe extraction. In this process variant, IEPs of 3.5 to 5 can beobtained.

Particularly low-peptide types of gelatin are obtained with a shortresidence time in the asher. Types of gelatin with high to averagemolecular weight distribution (M=10⁴ -10⁷ D) can thus be obtained.

Low molecular weight to cold water-soluble types of gelatin can beobtained by thermal degradation or enzymatically.

As already mentioned at the beginning and as is evident from FIG. 1, theabsolute, maximum possible net charge of an individual gelatin moleculedepends mainly on the number of free COOH and NH₂ groups and the pH ofthe solution. As Type A, B, collagen hydrolyzates or gelatin derivativesdiffer in the number of free COOH groups, their maximum possible netcharge is thus also different. With gelatin derivatives, the state ofcharge can additionally depend on the type of modification.

When carrying out the process according to the invention, the suitablegelatin and the suitable pH are selected in a preliminary test.

First, a working pH range suited to the physicochemical properties ofthe pharmaceutical substance is selected. Physicochemical properties ofthe pharmaceutical substance to be taken into account in particular are:the solubility (in organic solvents or water), its properties as anacid, base or neutral substance and its stability to acids and alkalisolutions.

In a first rapid test it is determined what charge the precipitatedparticles have. This results, taking into account the working pH range,in the choice of a suitable type of gelatin. If the particles are, forexample, negatively charged, a gelatin is picked which is positivelycharged under the given pH conditions. This rapid test for thedetermination of the particle charge has the advantages that it can becarried out without a great outlay in terms of apparatus and time. Atimeconsuming and inaccurate zeta potential measurement can thus bedispensed with entirely.

In many cases, it will be adequate for this rapid test to convert twocommercially available Type A and B gelatins with an IEP of 9.5 or 3.5respectively and with peptide contents of <30% and a bloom number of200, which are furthermore designated as standard gelatins, into the solform at a pH of 6 (5% strength aqueous solution) and to dissolve thepharmaceutical substance in a water-miscible solvent, such as e.g.ethanol, isopropanol or acetone, and in each case to mix homogeneouslywith the gelatin solutions. At the same dose of the pharmaceuticalsubstance, in the case of the gelatin which is unsuitable in its stateof charge a colloidal system will either not form or immediately becomeunstable or the pharmaceutical substance will flocculate. If theresulting particles are negatively charged, they are stabilized ratherby the gelatin solution of Type A, which is positively charged at a pHof 6, than by the solution containing Type B gelatin; in contrast, inthis case Type B either will form no colloidal system or the system willimmediately destabilize. The flocculation of the particles can bemonitored e.g. via a simple turbidity measurement.

In this rapid test, the working pH range must be taken into account ineach case. Other gelatins can also be selected as standards, but theymust be selected in their IEP such that they carry an opposite netcharge at this pH (see also FIG. 1). In most cases, said standard Type Aand B gelatins are adequate for this rapid test.

Starting from the result of the preliminary experiment, the optimumconditions for the formation of the nanosols are determined by stepwisevariation of the IEPs by use of appropriate types of gelatin and of thepH of the solution in relatively small ranges (e.g. 0.1 pH steps), i.e.the stability optimum which is characterized by the isoionic point (IIP)must be found in order to guarantee an adequate stability for thepharmaceutical applications mentioned.

It can be the case that a stability of the nanosols which is acceptablewithin the meaning of the invention is already found in a relativelynarrow pH range (about 0.5 units) around the isoionic point, so anadjustment of this point itself is not absolutely necessary. On theother hand, several gelatins can also lead to the same, stable results.Thus, for example (Example 5) with the oral antidiabetic glibenclamidein the case of a Type B gelatin with an IEP of 5.5 the stability optimumcan be at a pH of 3.2, while in the case of a Type B gelatin with an IEPof 3.8 the stability optimum is at a pH of 2.2.

Characterized by a stability maximum, in both cases the isoionic pointwas reached (the dependence of the net charge on the pH and the IEP mustbe non-linear, as it is given by the pK_(a) value of the COOH or NH₃ ⁺groups present).

According to the invention, other macromolecular substances in additionto gelatin, collagen hydrolyzates, fractionated gelatin or gelatinderivatives can be added in small amounts (at most 5% by weight). Thesecan be amphoteric or charged substances, such as, for example, albumins,casein, glycoproteins or other natural or synthetic polypeptides. Inparticular cases, anionic polymers such as e.g. alginates, gum arabic,pectins, polyacrylic acids and others may also be suitable.

According to the invention, several processes for the preparation of thenanosols are proposed. These are an exemplary, incomplete list. Theperson skilled in the art can independently work out further variants inthe context of the present invention on the basis of his expertknowledge:

Process I

This can be used if the pharmaceutical substance is soluble in a mixtureof: a water-miscible organic solvent and water, or severalwater-miscible organic solvents and water:

a) a gelatin selected in the preliminary tests is converted into solform with water;

b) the pH of the solution found in the preliminary tests is adjusted;

c) one or more water-miscible, organic solvent(s), preferably ethanol,isopropanol or methanol, is/are added to this solution;

d) the pharmaceutical substance is added to the solution in solid formand dissolved;

e) the organic solvent(s) is/are removed, preferably by evaporating invacuo; the nanosol is formed during the course of this;

f) the colloidally disperse solution is then dried, preferably by spray-or freeze-drying.

The organic solvent has the aim of dissolving the pharmaceuticalsubstance and also changes the hydration shell of the gelatin molecules.

Process II

This embodiment can be used if the pharmaceutical substance is an acidor a base whose salt is soluble in water:

a) a gelatin selected in the preliminary tests is converted into the solform with H₂ O;

b) a pH is set which enables formation of the salt of the pharmaceuticalsubstance;

c) the pharmaceutical substance is dissolved in the gelatin sol withsalt formation;

d) by addition of alcohol or similar organic solvents, the hydrationshell of the gelatin molecules can be loosened;

e) by addition of a suitable amount of acid or base the pH is set whichleads to the formation of the isoionic point (IIP) and the nanosolresults;

f) the colloidally disperse solution is dried as in process I.

Stage d) is optional, but preferred.

Process III

This embodiment can be used if the pharmaceutical substance is a neutralsubstance:

a) a gelatin sol is prepared as described in (1) a) and b).

b) a second solution is prepared from a water-miscible organic solvent,preferably ethanol, methanol, isopropanol or acetone and thepharmaceutical substance.

c) the two solutions are combined.

d) the original solvent is removed and the colloidally disperse solutionis dried.

Process IV

a) As described in (I) a) and b).

b) A collodially disperse system is briefly formed with thepharmaceutical substance, but without gelatin, in a second solution.

c) The solution obtained in (b) is continuously combined with thegelatin solution.

In step (IV) c) the continuous mixing of the solutions described in (IV)a) and b) can be controlled particle size using a suitable process, suchas e.g. by laser light scattering (BI-FOQELS On-line Particle Sizer). Itis thus possible to continuously set a desired particle size.

All processes mentioned are also suitable for collagen hydrolyzates andgelatin derivatives and can be applied without problems on theindustrial scale.

The essential steps can largely run in an automated manner, it alsobeing possible to carry out processes I to III continuously.

A pharmaceutically administrable nanosol and a process for itspreparation with various embodiments is described above. The invention,however, relates very generally to a nanosol, i.e. a stable highlydisperse system of poorly water-soluble inorganic and/or organiccompounds with gelatin, which comprises

a) an inner phase of the inorganic and/or organic compound(s), which has(have) a particle size of 10 to 800 nm and possesses (possess) anegative or positive surface charge,

b) an outer phase of gelatin, collagen hydrolyzate or a gelatinderivative, which is positively or negatively charged,

c) an approximately or completely isoionic charge state of the inner andouter phase.

Such a nanosol can be present as a liquid, aqueous nanodispersion.However, it can also be present as a solid, resuspensiblenanodispersion. A nanosol is particularly preferred in which theinorganic and/or organic compound or organic compounds has (have) aparticle size distribution of less than 300 nm, in particular 10 to 100nm. With positively charged particles of the organic compound(s), thegelatin has a negative net charge, while with negatively chargedparticles of the organic compound(s) it has a positive net charge.

The process for the preparation of such a nanosol from poorlywater-soluble inorganic and/or organic compounds is carried out by theprocess which was described above in connection with the preparation ofpharmaceutically administrable nanosols.

The following examples are intended to illustrate the invention ingreater detail:

EXAMPLE 1

Pharmaceutical substance: ibuprofen (racemate), active compound acid

Gelatin type: commercially available, Type B, 170 bloom

Nanosol preparation: analogous to Process I

Weight ratio gelatin/pharmaceutical substance: 1.5:1

The working pH range for ibuprofen is preferably below its PK_(a) of4.6.

The preliminary test at pH 4.3 for determination of the surface chargeof the ibuprofen particles does not yield a nanosol with the standardgelatin Type B (IEP 3.5/200 bloom). Under identical test conditions thestandard gelatin Type A (IEP 9.5/200 bloom) yields a briefly stablenanosol, in which the ibuprofen particles present carry a negativesurface charge.

For the determination of the stability optimum, types of gelatin withvarious IEPs are then tested at various pHs below pH 4.3. The series ofmeasurements shows that a gelatin of Type B (IEP 4.9), which carries apositive net charge at pH 3, is best suited. The nanosol formedaccording to process I has a stability maximum suitable forpharmaceutical use.

500 g of a 3% strength aqueous gelatin solution of the abovementionedtype are brought to pH 3.

250 ml of 96% ethanol are added.

10 g of ibuprofen are dissolved in this mixture, then the organicsolvent is evaporated. The nanosol thus produced is then spray-dried andcan be processed to give the corresponding pharmaceutical form.

Particle size measurements using a BI-FOQELS On-Line Particle Sizerreveal to 65% particle sizes of 450 nm.

EXAMPLE 2

The procedure is as in Example 1, but a gelatin is used which has beenobtained according to Example III (gelatin preparation) having the samebloom value and the same IEP (4.9).

Particle size measurements reveal to 70% particle sizes of 265 nm.

EXAMPLE 3

Pharmaceutical substance: dexamethasone, neutral substance

Gelatin type: Type A, 220 bloom, preparation Example I

Nanosol preparation: analogously to Process III

Weight ratio gelatin/pharmaceutical substance: about 10:1

The preliminary test carried out at pH 7 analogously to Example 1reveals in the case of the neutral substance dexamethasone that a Type Agelatin is suitable.

A Type A gelatin (IEP 7.9) having a positive state of charge at pH 5.3yields the stability optimum.

500 g of a 7.5% strength aqueous gelatin solution of the type of gelatinspecified above is adjusted to pH 5.3 by addition of acid.

3.5 g of pharmaceutical substance are dissolved in 100 ml of acetone.

Both solutions are mixed and the resulting nanosol is spray-dried afterremoval of the organic solvent.

The average particle size of the nanosol is between 260 and 300 nm.

EXAMPLE 4

The nanosol is produced as in Example 3, but using a gelatin ofcommercially available grade with identical characteristic numbers.

The average particle sizes are in the range from 550 to 630 nm.

EXAMPLE 5

Pharmaceutical substance: glibenclamide, active compound acid

Gelatin type: Type B, 100 bloom, preparation

EXAMPLE III

Nanosol preparation: analogously to Process III Weight ratiogelatin/pharmaceutical substance: 100:1

The working pH range for the weak active compound acid glibenclamide ispreferably below its PK_(a) of 6.3 to 6.8.

The preliminary test according to the invention and the series ofmeasurements reveals an optimum with a Type B gelatin (IEP 3.8) at a pHof 2.2 for the isoionic charge state.

For nanosol preparation, 5 g of gelatin of the above type are thenconverted to 5% into the sol form with water.

50 mg of glibenclamide are dissolved in 30 ml of 96% ethanol andhomogeneously mixed with the aqueous gelatin solution.

The resulting nanosol is lyophilized after removing the organic solventon a rotary evaporator.

Average particle sizes are 130 nm.

EXAMPLE 6

Pharmaceutical substance: propranolol, active compound base

Gelatin type: Type B, 320 bloom, preparation Example II

Nanosol preparation: analogously to Process II

Weight ratio gelatin/pharmaceutical substance: 4:1

Working pH range: 9.2

Gelatin selected according to preliminary test: Type B, 320 bloom, IEP4.2

16 g of propranolol hydrochloride are dissolved at pH 3 in a warmgelatin solution (64 g and 640 ml of water). By addition of sodiumhydroxide solution a pH of 8.8 is set, at which a nanosol of thepropranolol base is formed. In this case the isoionic charge state isonly approximately achieved.

The average particle sizes vary more greatly and are in the range from650 to 780 nm.

EXAMPLE 7

Pharmaceutical substance: indometacin, active compound acid

Gelatin type: collagen hydrolyzate having a peptide content of 90%,preparation Example II

Nanosol preparation: analogously to Process II

Weight ratio gelatin/pharmaceutical substance: 5:1

The preliminary test is carried out as in Example 1, but at a pH of 4.0.

The stability optimum of the nanosol is achieved with the collagenhydrolyzate having an IEP of 5.2 and a pH of the aqueous pharmaceuticalsubstance/gelatin solution of 3.1.

150 g of the collagen hydrolyzate are dissolved in 2 l of distilledwater. 30 g of indometacin are suspended in this solution. The pH of thesystem is kept between 7 and 8 using sodium hydroxide solution. It isadditionally stirred until a completely clear solution is formed. Byaddition of a measured amount of hydrochloric acid, the pH is adjustedto 3.1, at which the nanosol spontaneously forms.

The nanosol solution obtained is concentrated and spray-dried. Thepowder obtained is processed to give an immediate-effect form.

Particle size measurement reveals to 70% particle sizes of less than 370nm.

EXAMPLE 8

Pharmaceutical substance: nifedipine, neutral substance

Gelatin type: commercially available, Type B, 60 bloom

Nanosol preparation: analogously to Process III

Weight ratio gelatin/pharmaceutical substance: 15:1

Preparation is carried out with protection from light (yellow light).

The preliminary test is carried out analogously to Example 1, but at apH of 6.0.

The following series of measurements for the determination of thestability optimum shows a Type B gelatin (IEP 4.7) at a pH of 5.5.

600 g of the completely deionized gelatin specified above and 40 g ofPVP K 15 are dissolved in 8 l of distilled water at 40° C. and adjustedto a pH of 5.5.

40 g of nifedipine are completely dissolved in 1.3 l of ethanol.

Both solutions are homogeneously mixed and the resulting nanosol isspray-dried after removal of the alcohol. The powder obtained is filledinto opaque hard gelatin capsules with a content of 10 mg of nifedipineper capsule.

The dissolution test (paddle) reveals 100% release after 9 minutes (75rpm/900 ml of 0.1N HCl).

The bioavailability is increased by 25% in vivo compared with aconventional capsule preparation containing micronized nifedipine.Maximum blood level values are achieved on average after 20 min.

EXAMPLE 9

Active compound: glibenclamide, active compound acid

Gelatin type: commercially available, Type B, molecular weight below 10⁴D

Nanosol preparation: analogously to Process III

Weight ratio gelatin/pharmaceutical substance: 35:1

The working pH range is below the pK_(a) of 6.3-6.8.

After carrying out the preliminary test according to the invention andthe series of measurements for the determination of the optimum type ofgelatin, a stability maximum with a Type B gelatin (IEP 3.8) at a pH of2.2 is determined.

500 g of the above gelatin are dissolved in 3 l of dist. water. A pH of2.2 is set by addition of hydrochloric acid.

13.89 g of glibenclamide are dissolved in 0.2 l of ethanol. The twosolutions are combined, whereupon the nanosol forms.

Particle size measurements reveal to 80% particle sizes of less than 380nm.

The organic solvent is removed in vacuo and the product is thenspray-dried.

The dried nanosol is shaped to give tablets with addition of customarytableting auxiliaries in an eccentric press. Tablets having a rapidinflux in each case with a content of 3.5 mg of glibenclamide result.

EXAMPLE 10

Active compound: glibenclamide, active compound acid

Gelatin type: Type B (IEP 3.8), 20 bloom, preparation Example III

Nanosol preparation: analogously to Process III

Weight ratio gelatin/active compound: 35:1

Preparation of the nanosol is carried out analogously to Example 9.

Particle size measurements reveal to 80% particle sizes of less than 180nm.

EXAMPLE 11

Active compound: indometacin, active compound acid

Gelatin type: commercially available, Type B, 60 bloom

Nanosol preparation: analogously to Process II

Weight ratio gelatin/active compound: 6:1

The working pH range is below the pK_(a) of 4.5.

After carrying out the preliminary test according to the invention andthe series of measurements for the determination of the optimum type ofgelatin, a stability maximum with a Type B gelatin (IEP 5.2) at a pH of3.1 is determined.

600 g of the above gelatin are dissolved in 10 l of dist. water. 100 gof indometacin are suspended in this gelatin solution. Sodium hydroxidesolution is added so that the pH of the system is set in the range 7-8.The mixture is additionally stirred until a clear solution is formed. Itis then adjusted to pH 3.1 by addition of hydrochloric acid, whereuponthe nanosol forms.

The water is removed by subsequent spray-drying. The dried nanosol isprocessed to give tablets in an eccentric press with the addition ofcustomary tableting auxiliaries. Tablets having a rapid influx in eachcase with an indometacin content of 50 mg result.

Particle size measurements (BI-FOQUELS on-line Particle-Sizer) revealaverage particle sizes of about 370 nm.

EXAMPLE 12

Analogously to Example 11, only the gelatin is mixed with 10 g ofpolyvinylpyrrolidone K 15 before preparation of the solution.

Particle size measurements reveal average particle sizes of about 390nm.

In a dissolution test according to USP (750 ml test volume, consistingof 1 part by volume of phosphate buffer pH 7.2 and 4 parts by volume ofwater, paddle, 100 rpm, 37° C.), a complete dissolution of the tabletresults within 15 minutes. In comparison with this, tablets from Example11 are investigated under identical test conditions and show dissolvingtimes which are 20% higher on average.

EXAMPLE 13

Active compound: indometacin, active compound acid

Gelatin type: collagen hydrolyzate (IEP 5.2), preparation according toExample II

Nanosol preparation: analogously to Process III

Weight ratio gelatin/active compound: 4:1

300 g of the gelatin specified above are dissolved in 3 1 of distilledwater and a pH of 3.1 is set.

75 g of indometacin are dissolved in 500 ml of isopropanol. Bothsolutions are combined and the organic solvent is removed by evaporationin vacuo, whereupon the nanosol forms.

The product is then lyophilized. The powder is obtained is filled intoopaque hard gelatin capsules having a content of 25 mg of indometacin ineach case.

In a dissolution test according to USP (750 ml test volume, consistingof 1 part by volume of phosphate buffer pH 7.2 and 4 parts by volume ofwater, rotating basket, 100 rpm, 37° C.), these capsules show a capsuledisintegration within 3 min.

We claim:
 1. A dosage formulation that provides for the release ofnanoparticles which comprises:(a) an inner phase that comprises at leastone nanoparticle compound having an average size ranging from 10 to 800nanometers; and (b) an outer phase that comprises a compound selectedfrom the group consisting of gelatin, collagen hydrolyzates and mixturesthereof; wherein said inner phase is negatively charged and said outerphase is positively charged when the dosage formulation is dissolved inan aqueous solution having a pH of less than 9.5 or said inner phase ispositively charged and said outer phase is negatively charged when saiddosage formulation is dissolved in an aqueous solution having a pH ofhigher than 3.5.
 2. The dosage formulation of claim 1, wherein saidnanoparticle is a pharmaceutical compound.
 3. The dosage formulation ofclaim 2, wherein the aqueous solubility of said pharmaceutical compoundis less than 5 g/l at room temperature.
 4. The dosage formulation ofclaim 1, wherein said nanoparticle has an average particle size of lessthan 400 nanometers.
 5. The dosage formulation of claim 1, wherein saidnanoparticle has an average particle size ranging from 10 to 100nanometers.
 6. The dosage formulation of claim 1, wherein the outerphase comprises gelatin.
 7. The dosage formulation of claim 1, which isa liquid, aqueous dosage formulation.
 8. The dosage formulation of claim1, which is a solid dosage formulation.
 9. The dosage formulation ofclaim 1, wherein the outer phase comprises gelatin and further comprisespolyvinylpyrrolidine and the weight ratio of gelatin topolyvinylpyrrolidine ranges from 5:1 to 500:1.
 10. The dosageformulation of claim 1, wherein said at least one nanoparticle compoundcontained is in the form of a solid powder and said powder is containedin a hard gelatin capsule.
 11. The dosage formulation of claim 1, whichis an immediate release medicament.
 12. The dosage formulation of claim11, which is suitable for the treatment of diabetes and wherein saidnanoparticle compound comprises glibenclamide.
 13. The dosageformulation of claim 11, which further comprises at least onepharmaceutical excipient or auxiliary.
 14. The dosage formulation ofclaim 12, which further comprises at least one pharmaceutical excipientor auxiliary.
 15. The dosage formulation of claim 1, wherein saidgelatin comprises a bloom value ranging from 0 to
 240. 16. The dosageformulation of claim 15, wherein said gelatin comprises a bloom valueranging from 0 to
 170. 17. The dosage formulation of claim 1, whereinsaid gelatin has a maximum average molecular weight of 10⁵ daltons. 18.The dosage formulation of claim 1, wherein said gelatin has a peptidecontent ranging from 50 to 90%.
 19. The dosage formulation of claim 1,wherein said gelatin has an average maximum molecular weightdistribution ranging from 10⁴ to 9.5×10⁴ daltons.
 20. The dosageformulation of claim 1, wherein the outer phase comprises gelatin andthe weight ratio of gelatin to said at least one nanoparticle compoundranges from 1:1 to 200:1.
 21. The dosage formulation of claim 1, whichcomprises an immediate-release formulation and a sustained-releaseformulation.
 22. The dosage formulation of claim 1, wherein said atleast one nanoparticle compound comprises indomethacin.
 23. The dosageformulation of claim 1, wherein said at least one nanoparticle compoundcomprises acemetacin.
 24. The dosage formulation of claim 1, whereinsaid gelatin has a dextrorotatory amino acid content which is less than20%.
 25. The dosage formulation of claim 1, which comprises a hardgelatin capsule containing powder and a tablet wherein the powder has amore rapid dissolution rate when dissolved in an aqueous solution thanthe tablet.
 26. The dosage formulation of claim 10, wherein said atleast one nanoparticle compound contained in said inner phase has anaverage particle size of less than 400 nanoparticles.
 27. The dosageformulation of claim 1, wherein the charge of said outer phaseneutralizes the charge of said inner phase.
 28. The dosage formulationof claim 1, wherein said outer phase further comprises a liquid or driedpharmaceutical auxiliary.
 29. The dosage formulation of claim 28,wherein the ratio of said auxiliary to said gelatin, collagenhydrolyzate or mixture ranges from 5:1 to 500:1.
 30. The dosageformulation of claim 29, wherein said weight ratio ranges from 5:1 to30:1.
 31. The dosage formulation of claim 1 which is suitable forpharmaceutical administration.